IMHO HP is probably the best choice. You can get direct flights in and out of SFO, OAK, and SJC with a number of flights per location per day. WN doesn't fly to SFO and is a major pain at OAK. UA (Ted) does fly direct, but not with the same frequency.

Depending on the location and time she'll either get an A319, 757, or 737. The A319s are by far the newest and nicest. The 737s are starting to get a little ratty. For a 1:45 flight none of them are bad.

For short-haul stuff HP has proven to be the best choice for me (free FC upgrades for elite members are nice), but it doesn't give me many options for travel outside of the US. In my case I don't have an oportunity to rack up a lot of miles since the longest flight I take is PHX - PDX. I am accumulating miles, but as of yet, don't see any major use for them. I just burned 40K for some first class upgrades over the holidays, but that's all that I've ever done.

I liked WN's program, but eventually realized that I wasn't going to use the free tickets for personal travel as I really hate flying that airline. I burnd a couple of free tickets, but for the most part I just let them expire.

I'm leaving it up to AMEX to satisfy my desire for free tickets to exotic locations. Everything else that I do is close (< 1000 miles) and cheap (< $200).